<!doctype html>
<html lang="en">
  <head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <title>Bootstrap demo</title>
    <link href="https://cdn.staticfile.org/twitter-bootstrap/4.3.1/css/bootstrap.min.css" rel="stylesheet">
    <script src="https://cdn.staticfile.org/twitter-bootstrap/4.3.1/js/bootstrap.min.js"></script>
    <script src="https://cdn.staticfile.org/jquery/3.2.1/jquery.min.js"></script>
  </head>
  <body>
    <div class="col-6 card p-5">
        <div class="bg-secondary mb-2 p-2" align="center"><h4>注册界面</h4></div>
        <form role="form">
          <!-- 注册用户名 -->
          <div class="input-group mb-3">
            <div class="input-group-prepend">
              <span class="input-group-text" id="basic-addon1">用户名</span>
            </div>
            <input type="text" class="form-control" placeholder="请输入用户名称" />
          </div>
          <!-- 密码 -->
          <div class="input-group mb-3">
            <div class="input-group-prepend">
              <span class="input-group-text" id="basic-addon1">密码</span>
            </div>
            <input type="password" name="pwd" id="pwd" class="form-control" placeholder="请输入密码" />
          </div>
          <!-- 确认密码 -->
          <div class="input-group mb-3">
            <div class="input-group-prepend">
              <span class="input-group-text" id="basic-addon1">确认密码</span>
            </div>
            <input type="password" name="pwd" id="pwd" class="form-control" placeholder="请输入确认密码" />
          </div>
          <!-- 选择城市 -->
          <div class="input-group mb-3">
            <div class="input-group-prepend">
              <span class="input-group-text" id="basic-addon1">城市</span>
            </div>
            <select class="form-control" name="cities" id="cities">
                <option value="0">天津</option>
                <option value="1">北京</option>
                <option value="2">上海</option>
            </select>
          </div>
          <!-- 注册按钮 -->
          <button type="button" class="btn btn-primary">登录</button>
        </form>
      </div>
  </body>
  </html>